function lazyload(){
    var temp1 = window.innerHeight || document.documentElement.clientHeight
    var temp2 = document.body.scrollTop || document.documentElement.scrollTop
    var maxShowHight = temp1 + temp2
    var imgObjs = document.querySelectorAll('img')
    imgObjs.forEach(function(item){
        if(item.offsetTop <= maxShowHight){
            item.src = item.getAttribute('data')
        }
    })
}